But if I did something above and beyond to help you out of a tough situation and you compensated me unexpectedly.  

Any other unexpected costs?

into just a few of my properties that had very unexpected expensive maintenance issues.

Any unexpected twists or lessons you wish you knew before diving in?

In case of an unexpected expense and a required cash infusion from the partners, any thoughts on how that is handled best?

But my original estimates on cash-on-cash is coming down to 17% which I know will likely be lower when I factor in unexpected repairs.

By NOT having a reserve funding plan, more often than not the only option is an unexpected "Special Assessment".

When the suboptimal, generic branding is combined with suboptimal, generic flavor of technical issues and inflexibility that others mentioned above, especially sending notices to tenants unexpectedly and blind, it becomes an absolute deal killer for me. 

Not to mention, it makes our own processes more efficient to know that we are not going to deal with any unexpected events or delays from an unfamiliar lender.

There can be more money in crushing an illegal seller than in a car accident!